1. Field of the Invention
The present invention relates to a method and apparatus for determining concentrations of organic additives in metal plating solutions, based on spectroscopy, and more specifically attenuated total reflection (ATR) spectroscopy.
2. Background of the Invention
The recent switch from aluminum to copper interconnects in semiconductor industry has lead to the development of a large variety of new copper plating solutions containing various organic additives, including suppressor, accelerator, and leveler. The finer scale of the metal patterning and the use of automatic manufacturing techniques demand a faster and more precise control of the composition of the metal plating solution, especially with respect to the concentrations of the organic additives in such metal plating solution, which have significant impact upon the quality of the metal finish layer. Current analytical techniques used for the process control in metal plating, such as chromatography and electro-potentiometry, are time-consuming and expensive, and lack selectivity for specific organic additive species.
It is an object of the present invention to provide an analytical method and apparatus for determining the organic additive concentration in metal plating solutions, which is less time-consuming, requiring minimal or no sample preparation, and having excellent selectivity and sensitivity for specific organic additive species.
Other objects and advantages will be more fully apparent from the ensuing disclosure and appended claims.